Sanitary pump with removable port bridges



' 1968 A. v. SEGELHORST ETAL 3,364,867

SANITARY PUMP WITH REMOVABLE PORT BRIDGES Filed Jan. 14, 1966 3 Sheets-Sheet 1 I NVENTORS.

AUGUST M55641 HORST 60200 H. BRHDFORD BY THE/P HTTORIVEYS. HF) R/P/S, ff/scH, RUSSELL 9: KER/v Jan. 23, 1968 A. v. SEGELHORST ETAL 3,354,867

ANITARY PUMP WITH REMOVABLE PORT BRIDGE 3 Sheets-Sheet Filed Jan. 14, 1966 Era. 2.

INVENTORS.

IQUGUST MSEGELHORST oxwo/v H. BRADFORD BY THlZ/l? HTTORNEYS.

HFMRl-S; K/EcH, RUSSELL & KER/V 1963 A. v. SEGELHORST ETAL 3,364,867

SANITARY PUMP WITH REMOVABLE PORT BRIDGES Filed Jan. 14, 1966 a Sheets-Sheet :s

INVENTORS. Hue-U57 M SEGELHOIFST 60200 H. BRADFORD BY THE/f? HTTORNEYS. HER/PIS, lf/ecH, /?U$SLL i/(ER/v United States Patent 3,364,867 SANITARY PUM? WITH REMOVABLE PORT BRIDGES August V. Segelhorst, Corona Del Mar, and Gordon H.

Bradford, Costa Mesa, Califi, assignors, by mesne assignments, to International Telephone and Telegraph Corporation, a corporation of Maryland Filed Jan. 14, 1966, Ser. No. 520,627 Claims. (Cl. 193-117) The present invention relates to a rotary pump having flexible elastomeric vanes which alternately straighten and bend to pump fluid from an inlet port to an outlet port, and a primary object of the invention is to provide a sanitary pump of this type having easily-cleaned means for supporting the outer edges of the bendable vanes as they slide across one or both of the inlet and outlet ports.

As background, the invention contemplates a flexiblevane pump of the type which includes: a housing provided therein with an impeller chamber having a peripheral wall and having an impeller axis; an impeller rotatable in the impeller chamber about the impeller axis and provided with bendable elastomeric vanes having outer edges slidable along the peripheral wall of the impeller chamber as the impeller rotates therein; inlet and outlet cam surfaces respectively integral with and forming parts of the peripheral wall of the impeller chamber and respectively having increasing and decreasing radii, measured from the impeller axis, in the direction of rotation of the impeller; and radial inlet and outlet ports respectively formed in the inlet and outlet cam surfaces. With this construction, the elastomeric vanes are bent by the outletcam surface as the outer edges of the vanes slide therealong, thereby reducing the volumes of the intervane spaces to expel fluid therefrom into the outlet port. Conversely, as the outer edges of the vanes slide along the inlet cam surface, the vanes straighten to increase the volumes of the intervane spaces, and thus draw additional fluid thereinto from the inlet port.

With a pump construction of the foregoing character, there is a tendency for the outer edges of the vanes to deform radially outwardly into one or both of the ports, this being particularly true of the outlet port because of the pressures created within the decreasing-volume intervane spaces. Such radially outward deformation into one or both ports, which deformation apparently takes the form of radially-extending folds in the vanes, causes undesirable wear of the vanes.

In flexible-vane pumps which need not be kept sanitary, it is conventional to utilize separate cams having comblike edges providing fingers which span the inlet and outlet ports in the direction of impeller rotation to support the outer edges of the vanes as they slide across the inlet and outlet ports, thereby minimizing wear of the outer edges of the vanes. However, this construction cannot be used in sanitary pumps, for pumping milk or other fluids which must be kept sanitary, because it cannot be cleaned satisfactorily, there being numerous relatively inaccessible surfaces which act as bacteria traps.

In view of the foregoing sanitation problems with conventional pump constructions, it has been the practice to utilize unbridged inlet and outlet ports. However, as hereinbefore outlined, this practice results in undesirable wear of the elastomeric vanes.

With the foregoing as background, the primary object of the invention, as hereinbefore indicated, is to provide a flexible-vane pump which can be cleaned easily utilizing the methods conventionally employed in connection with sanitary pumps, but which supports the outer edges of the vanes as they traverse one or both ports, and partic ularly the outlet port.

More specifically, an important object of the invention is to provide removable bridge means positioned in the desired port and supporting the outer edges of the vanes as they slide across such port, together with means for positively securing the bridge means in place in a manner permitting easy removal for cleaning. A related object is to provide means for removably securing the bridge means is place upon disassembly of the pump, the bridge means nevertheless being readily removable from the port for cleaning.

Another and important object of the invention is to provide a bridge means of the foregoing nature which may be used with existing pump designs so that no drastic redesign is necessary, and which may be made of any appropriate material, such as stainless steel, a suitable plastic, or the like.

Still another important object of the invention is to provide a bridge means having substantially only line or point contact with the walls of the port in which it is disposed, thereby insuring effective cleaning when a cleaning solution is circulated through the pump. A related object in connection with certain species of the invention is to provide lines of engagement between the bridge means and the side walls of the port which extend in the direction of flow through the port to facilitate cleaning.

Another object is to provide a bridge means which includes at least one bridge surface slidably engageable by the outer edges of the vanes and extending in the direction of sliding movement of the outer edges of the vanes across the port. A related object is to provide interengageable means on the bridge means and the pump housing for maintaining the bridge surface oriented in the direction, of sliding movement of the outer edges of the vanes across the port.

A further object is to provide a bridge means which includes resilient elements biased laterally outwardly into engagement with the side walls of the port and providing bridge surfaces slidably engageable by the outer edges of the vanes. With this construction, the bridge means is simply pressed into the corresponding port, the inherent resilience of the bridge elements holding the bridge means in place. Related objects are to provide such a bridge means having bridge elements which are blades, wires, or the like.

Anonther object is to provide detents on the bridge means insertable into detent recesses in the side walls of the port, the detents making only point or line contact with their recesses to facilitate cleaning.

Yet another object of the invention is to provide a bridge means which includes a tubular bridge element spaced laterally inwardly from the side walls of the port and terminating at its radially inner end in an annular bridge surface substantially concentric with the port and slidably engageable by the outer edges of the vanes. A related object is to provide supporting means for the tubular bridge element which makes only substantially line contact with the side Walls of the port.

The foregoing objects, advantages, features and results of the present invention, together with various other objects, advantages, features and results thereof which will be evident to those skilled in the flexible-vane sanitary pump art in the light of this disclosure, may be achieved with the exemplary embodiments of the invention described in detail hereinafter and illustrated in the accompanying drawings, in which:

FIG. 1 is a transverse sectional view of a sanitary pump which embodies the invention;

FIG. 2 is an inner end view of a port of the pump showing various desirable structural characteristics;

FIG. 3 is a sectional view in a plane containing the axis 3 of a port of the pump showing other desirable structural characteristics;

FIGS. 4 and 5 are enlarged sectional views respectively taken along the arrowed lines 4-4 and 5-5 of FIG. 1;

FIG. 6 is an enlarged, fragmentary sectional view taken as indicated by the arrowed line 66 of FIG. 1;

FIG. 7 is an enlarged, fragmentary sectional view taken as indicated by the arrowed line 7-7 of FIG. 4;

FIG. 8 is an isometric view of a port bridge or bridge means which is shown in FIGS. 1 and 4 to 6;

FIG. 9 is an isometric view showing a port bridge or bridge means which is a modification of the one shown in FIG. 8;

FIG. 10 is an inner end view of another port bridge or bridge means of the invention;

FIG. 11 is a sectional view taken as indicated by the arrowed line lit-11 of FIG. 10;

FIG. 12 is a fragmentary sectional view, in a plane containing the axis of a port of the pump, showing another port bridge or bridge means of the invention;

FIG. 13 is a fragmentary elevational view showing the inner end of the port bridge or bridge means of FIG. 12;

FIG. 14 is a view similar to FIG. 13, but showing a modification of the port bridge or bridge means of FIG. 13;

FIG. 15 is a fragmentary sectional view in a plane containing the axis of a pump port showing still another port bridge or bridge means of the invention;

FIG. 16 is an inner end view of the port bridge or bridge means of FIG. 15;

FIG. 17 is an inner end view of a pump port having therein yet another bridge means of the invention;

FIG. 18 is a fragmentary sectional view taken as indicated by the arrowed line 18-18 of FIG. 17;

FIG. 19 is an inner end view of a pump port having therein still another bridge means of the invention;

FIG. 20 is a fragmentary sectional view taken as indicated by the arrowed line 20-20 of FIG. 19;

FIG. 21 is an inner end view of a pump port having therein yet another bridge means of the invention; and

FIG. 22 is a fragmentary sectional view taken as indicated by the arrowed line 2222 of FIG. 21.

Referring initially to FIG. 1 of the drawings, illustrated therein is a sanitary pump 30 comprising a housing 32 provided therein with an impeller chamber 34 having an impeller axis 36 about which an elastomeric impeller 38 is rotatable, the impeller having bendable elastomeric vanes 40 the ends of which slidably engage the end walls of the impeller chamber and the outer edges of which slidably engage the peripheral wall thereof. The peripheral wall of the impeller chamber 34 has surfaces 42 and .4 of maximum and minimum radius, measured from the impeller axis 36. The peripheral wall of the impeller chamber 34 further includes cam surfaces 46 and 48 of varying radius, which interconnect the maximum-radius and minimum-radius surfaces 42 and 44.

The housing 32 is provided with generally radial ports 56 and 52 the inner ends of which are formed in the respective cam surfaces 46 and 48. The housing 32 is provided at the outer ends of the ports 50 and 52 with frusto-conical seats 54 and 56 for frusto-conical inner ends 58 and 60 of tubes or pipes 62 and 64 communicating with the respective ports 50 and 52. The pipe 62 is shown as removably secured to the pump housing 32 by an annular clamp 66 embracing annular flanges 68 and 70 on the housing and the pipe 62, respectively. The pipe 64 is shown as removably secured to the pump housing 32 by a nut 72 threaded on annular flanges 74 and 76 on the pump housing and the pipe 64, respectively.

As illustrated in FIG. 1 of the drawings, the impeller 38 is driven in the counterclockwise direction in any suitable manner, well known in the art. The blades or vanes 40 of the impeller 38 bend as they slide from the maximum-radius surface 42 over the cam surface 48 onto the minimum-radius surface 44. Conversely, the blades or vanes 40 straighten as they slide from the minimum-radius surface 44 over the cam surface 46 onto the maximum-radius surface 42. Thus, for the particular counterclockwise direction of rotation shown, the volumes of the intervane spaces increase as the vanes 40 pass the port 50, and decrease as they pass the port 52. Consequently, the fluid to be pumped is drawn into the intervane spaces from the port 50, and is expelled therefrom into the port 52.

Thus, for the particular counterclockwise direction of impeller rotation shown, the port 50 is the inlet port and the port 52 is the outlet port. Correspondingly, the cam surface 46 acts as an inlet cam surface the radius of which increases in the direction of impeller rotation, and the cam surface 48 acts as an outlet cam surface the radius of which decreases in the direction of impeller rotation. For convenience, the ports 50 and 52 and the cam surfaces 46 and 48 will be regarded hereinafter as inlet and outlet ports and inlet and outlet cam surfaces, respectively. However, it will be understood that if the direction of impeller rotation is reversed, the ports 50 and 52 and the cam surfaces 46 and 48 have their functions reversed.

As thus far described, the pump 30 is a conventional sanitary pump which can be disassembled readily for cleaning and which has substantially no inaccessible surfaces capable of acting as bacteria traps. However, such a conventional sanitary pump has one serious shortcom ing, which is the tendency of the outer edges of the vanes 40 to deform radially outwardly into the ports 50 and 52, this being particularly true of the outlet port 52 because of the pressures created within the decreasingvolume intervane spaces opposite such port. Such radially outward deformation into the ports 50 and 52, and particularly the outlet port 52, which deformation apparently takes the form of radially-extending buckles or folds in the vanes, causes undesirably rapid wear of the vanes.

In flexible-vane pumps which need not be kept sanitary, it is conventional to incorporate the minimum-radius surface 44 and the inlet and outlet cam surfaces 46 and 48 in a separate cam having comb-like edges providing fingers which span the inlet and outlet ports the direction of vane movement to support the outer edges of the vanes as they slide across the inlet and outlet ports, thereby minimizing wear of the outer edges of the vanes. However, this construction cannot be used in sanitary pumps, for pumping milk, or other fluids which must be kept sanitary, because it cannot be cleaned satisfactorily, there being numerous relatively inaccessible surfaces which act as bacteria traps.

The primary object of the present invention is to pro vide a flexible-vane pump 30 which can be cleaned easily utilizing the methods conventionally employed in con nection with sanitary pumps, but which adequately sup ports the outer edges of the vanes 40 as they traverse one or both of the ports 50 and 52, and particularly the outlet port 52. For convenience, the invention will be considered hereinafter as applied to the outlet port 52 only, with the understanding that it can be applied to the inlet port 50 as well.

Before considering the invention in detail, 'it is convenient to consider various desirable structural factors as background. Referring to FIG. 2, the outlet port 52 is shown therein as a circular port having a diameter D, and the direction of movement of the vanes 40 across the port 52 is indicated by the double-headed arrow 80. The dimensional lines D/2, drawn perpendicular to the direction 80 of vane movement, are chords having a length equal to one-half the port diameter D. The dimensional arrow 82 indicates the distance between the chords D/2.

To minimize Wear of the vanes 40 to the optimum degree, it is desirable to support the outer edges thereof, as they sweep across the inner end of the port 52, throughout at least the distance indicated by the dimensional arrow 82. However, substantial reductions in vane Wear can be achieved with support for the outer edges of the vanes 40 throughout distances less than that indicated by the dimensional arrow 82. One object of the present invention is to provide support for the outer edges of the vanes 40 throughout at least a substantial portion of the distance indicated by the dimensional arrow 82 to achieve satisfactory reductions in vane wear. It will be noted that the various embodiments of the invention hereinafter described in detail provide support for the outer edges of the vanes 41 throughout distances ranging from substantial portions of the distance indicated by the dimensional arrow 82 all the way to the full diameter D of the port 52. This will be evident from the illustrations of the various embodiments of the invention in the drawings, and need not be discussed further herein.

Referring to FIG. 3, the first and last extremities of the inner end of the port 52 which are engaged by the outer edges of the vanes 40, as they sweep across the inner end of the port, are shown as lying in a plane 84 perpendicular to the axis 8% of the port. With this construction, adequate support for the outer edges of the vanes 46 can be obtained even with straight bridge surfaces located entirely within the port 52, i.e., outwardly of the inner end of the port, and parallel to the plane 84. In other words, the outer edges of the vanes 46 are supported throughout a substantial portion of their sweep across the inner end of the port 52 with this construction. As will become apparent, various of the embodiments of the invention illustrated in the drawings take advantage or this feature, examples being the various species illustrated in FIGS. 9 to 16 of the drawings.

Adverting to FIG. 1 of the drawings, and considering FIG. 1 in conjunction with FIGS. 4 to 8, the port 52 is shown as provided therein with a readily removable bridge or bridge means 96 for supporting the outer edges of the vanes 40 as they slide across the inner end of the port 52. The bridge 99 comprises a bridge element 92 having the form of a flat blade the width of which is substantially equal to the diameter of the port 52. The bridge element 92 is provided with rounded longitudinal edges 94 which have only line engagement with the peripheral wall of the port 52, the lines of engagement extending in the direction of flow through the port. With this construction, bacteria traps are avoided, and cleaning can be accomplished with the bridge 90 in place by circulating a cleaning fluid through the pump 30 in the conventional manner.

The bridge element 92 is provided at its outer end with an outwardly flared portion 96 the edges of which are seated in grooves 98 in the seat 56 at the outer end of the port 52. With this construction, the bridge element 92 is so oriented that a bridge surface 190 at its inner end is maintained parallel to the direction of movement of the outer edges of the vanes 40 across the port 52. Also, radial insertion of the bridge surface 100 beyond the desired position is prevented by this construction. The edges of the outwardly flared portion 96 of the bridge 90 are rounded so that they make only line contact with the bottoms of the grooves 98, in the direction of flow through the port 52. Again, this eliminates bacteria traps and facilitates cleaning in place.

The bridge surface 109 of the bridge element 92 supports the outer edges of the vanes 40 as they sweep across the inner end of the outlet port 52. It will be noted that the bridge surface has a contour conforming to that or the cam surface 48, and is flush with this cam surface, so that it provides support for the outer edges of the vanes 41 all the way across the inner end of the port 52. Thus, this embodiment exceeds the minimum desired support hereinbefore discussed in connection with FIG. 2 of the drawings.

Referring to FIG. 9, illustrated therein is a bridge 102 which is similar to the bridge 90, but which is provided at its inner end with a bridge surface 104 perpendicular to the longitudinal axis of the bridge. In use, the bridge 6 surface 104 is positioned slightly within the inner end of the port 52 (as in the embodiment of FIG. 12, for example) with the bridge surface 104 parallel to the perpendicular plane 84 of FIG. 3. Thus, as discussed in connection with FIG. 3, the bridge surface 104, even though it is perpendicular to the longitudinal axis of the bridge 102 and is disposed slightly within the port 52, still provides support for the outer edges of the vanes 40 during a substantial portion of their sweep across the inner end of the port 52. Such support is sufiicient to reduce vane wear significantly.

It will be noted that either of the bridges and 102 will remain in place in the port 52 even though the connection between the pipe 64 and the pump housing 32 is broken. However, either bridge 90 or 102 can be withdrawn from the port 52 readily if necessary for cleaning. This is a desirable feature since the fact that the bridge 90 or 192 will remain in place in the port 52 until removed facilitates assembly and disassembly of the pump 30. As will become apparent hereinafter, the embodiments of the invention to be described similarly remain in place in the port 52 until removed. Consequently, this point need not be considered further herein in connection with the remaining embodiments.

Referring to FIGS. 10 and 11 of the drawings, illustrated therein is a bridge or bridge means comprising a frusto-conical ring 112 engageable with the frusto-conical seat 56. For orientation purposes, the ring 112 is provided with a rib 114 receivable in a groove (not shown) in the seat 56 corresponding to one of the grooves 98. The ring 112 carries two laterally spaced bridge elements 116 terminating at their inner ends in bridge surf-aces 118 similar to the bridge surface 104. The bridge elements 116 normally occupy the positions suggested by dotted lines 120 in FIG. 11. Consequently, when the bridge 110 is pressed into the port 52, the inherent resilience of the bridge elements 116 holds the bridge in place in the port.

As in the case of the bridge 90, the elements 116 of the bridge 11% have rounded longitudinal edges making only line contact, in the direction of flow, with the peripheral wall of the port 52. Similarly, the rib 114 preferably makes only line contact, in the direction of flow, with the wall of the groove in which it is disposed. This construction avoids bacteria traps and is conducive to cleaning of the bridge 116 in place by circulation of a cleaning fluid through the pump 30. For similar reasons, the interior surface of the ring 112, and the junctions between the ring and the bridge elements 116, are streamlined, as shown in FIG. 11. If desired, the outer surface of the ring 112 may be provided with projections, similar to those shown on the ring in FIGS. 15 and 16, for spacing the outer surface of the ring 112 outwardly from the frusto-conical seat 56, such projections making substantially only point contact with the seat 56. With this construction, there can be no bacteria traps between the ring 112 and the seat 56, and the space therebetween is easily cleaned with a circulating fluid.

Turning to FIGS. 12 and 13 of the drawings, the port 52 is shown as provided therein with a bridge or bridge means which, in this case, includes a tubular bridge element 132 spaced laterally inwardly from and concentric with the peripheral wall of the port. The tubular bridge element 132 is provided with a flat end constituting a bridge surface 134 just within the port 52 and parallel to the plane 84 hereinbefore discussed in connection with FIG. 3. With this construction, the bridge surface 134 provides support for the outer edgesof the vanes 40 during a substantial portion of their sweep across the inner end of the port 52, thereby significantly reducing wear.

The tubular bridge element 132 is supported concentrically within the port 52 by two plates 136 suitably secured thereto, these plates terminating some distance outwardly from the inner end of the port 52. As will be apparent from FIG. 13, the edges of the plates 136 make only line engagement with the peripheral wall of the port 7 52, in the direction of flow through the port. Similarly, the plates 136 make only line engagement with the tubular bridge element 132, again in the direction of fluid flow. Consequently, no bacteria traps are formed, and easy cleaning in .place is possible.

In FIG. 14 of the drawings is shown a bridge or bridge means 140 which is similar to the bridge 130 and which includes a similar, concentric, tubular bridge element 142. In this case, the bridge element 142 is held in place by three plates 1'44 equally spaced apart circurnferentially of the port and each corresponding to one of the plates 136. In view of the similarities between the bridge 148 and the bridge 130, it is thought that no further description of the bridge 140 is necessary. It might be pointed out in passing that both the bridges 130 and 148 are frictionally held in place in the port 52 until removal for cleaning is desired.

Going to FIGS. 15 and 16 of the drawings, illustrated therein is a bridge or bridge means 150 comprising a streamlined, frusto-conical ring 152 spaced inwardly from the frusto-conical seat 56 by circumferentially spaced projections 154 making substantially point contact with the seat 56 to avoid bacteria traps and to facilitate cleaning. Formed integrally with or suitably secured to the ring 152 are three ciroumferentially spaced, radial blades 15:) having at their inner ends bridge surfaces 158 just within the inner end of the port 52 and parallel to the hereinbefore-discussed plane 84 of FIG. 3. With this construction, the bridge surfaces 158 provide a composite support for the outer ends of the vanes 40 throughout a substantial portion of their sweep across the inner end of the port 52, as will be apparent from FIG. 15 of the drawmgs.

The inner ends of the blades 156 are biased radially outwardly relative to each other by the inherent resilience of the bridge 154). The blades 156 are provided adjacent their inner ends, and on their outer edges, with radiallyoutwardly extending detents 160 respectively receivable in detent recesses 162 (or an annular detent groove) in the peripheral Wall of the port 52. The detents 160 and recesses 162 are rounded so that the detents make substantially only point contact with the walls of the recesses, thereby avoiding bacteria traps and facilitating cleaning. As will be apparent, when the bridge 150 is inserted into the port 52, the detents 160 snap into the recesses 162 to hold the bridge in place within the port until removal is desired. The recesses 162 may be separate recesses, or, as suggested above, the peripheral wall of the port 52 may be provided with an internal annular groove to receive the detents 160, this latter construction being preferred since it is less likely to produce bacteria traps. Although three blades 156 are shown, this number may be varied. Also, if there are more than three blades, it is not necessary that all of them have detents. Further, additional blades (not shown) centrally supported, as on a central post or tube, may be used.

Turning to FIGS. 17 and 18 of the drawings, illustrated therein is a bridge or bridge means 170 of the invention which is made of a single piece of wire, or the like. More particularly, the bridge 170- includes three legs 172, 174 and 176 arranged in generally trapezoidal form, the legs 174 and 176 terminating in bridge elements 178 and 180 disposed radially inwardly of the port 52 with respect to the leg 172. As shown in FIG. 18, the bridge elements 178 and 180 have substantially the same contour as and. are substantially flush with the cam surface 48, and provide support for the outer edges of the vanes 40 throughout substantially their entire sweep across the inner end of the port 52.

The two trapezoid corners which are located at the junctions of the legs 174 and 176 with the leg 172 act at detents and are disposed in detent recesses 182 and 184 in the peripheral wall of the port 52 adjacent the inner end thereof. The other two corners of the trapezoid also act as detents and are disposed in a common circumferentially elongated detent recess 186 in spaced apart relation. Thus, the four corners of the trapezoid act as detents receivable in the detent recesses 182, 184 and 186.

As will be apparent, the bridge may be removed readily by forcing the two corners of the trpezoid which are in the recess 186 toward each other sufiiciently to permit withdrawal of such corners from the recess 186.

Thereupon, the other two corners may be withdrawn from the recesses 182 and 184. The bridge 170 may be installed and removed readily with a suitable pliers-like tool.

bridge or bridge means 196 also composed of a single piece of wire, or the like. In this case, the bridge 190 is shown as generally Y-shaped and as having detent extremities 192, 194 and 1% respectively disposed in detent recesses 198, 288 and 202 in the peripheral wall of the port 52 adjacent the inner end thereof. The generally bridge or bridge means 219' of wire, or the like, which has the general configuration of a trapezoid or truncated triangle, being similar to the trapezoidal portion of the bridge 170. More particularly, the bridge 210 has legs 212, 214 and 216, the junctions of the legs 214 and 216 with the leg v212 forming detent corners. disposed in detent recesses 218 and 220 in the peripheral wall of the port 52'adjacent the inner end of the port. The free ends of the legs 214 and 216' are disposed in a circumferentially elongated detent recess 222 similar to the detent recess 186 of FIGS. 17 and 18. The bridge 210 may be installed and removed in much the same manner ,as the bridge 174). The outer edges of the vanes 40 engage the legs 212, 214 and 216 of the bridge 210 as they sweep across the inner end of the port 52, thereby providing support for the outer edges of the vanes.

All three wire bridges 170, 190 and 210 preferably make substantially point contact with the pump housing 32 at the points where the detent portions thereof contact the walls of the corresponding detent recesses, such detent portions being rounded for this purpose. This avoids bacteria traps and facilitates cleaning in place. Preferably, the wire of which the bridge 210 is formed is oval or elliptical in cross section, with the long axis of.

the oval or ellipse parallel to the direction of flow; This further eliminates bacteria traps, and facilitates cleaning. A similar oval or elliptical cross section may be employed for the wires of the bridges 170 and 190 if desired. Further, all of these bridges may be contoured to conform to the cam surface 48.

All of the bridges herein disclosed may be made of any suitable easily cleaned material, stainless steel and appropriate plastics being examples, which is inert with respect to the fluid being pumped.

Although exemplary embodiments of the invention have been disclosed herein for purposes of illustration, it will be understood that various changes, modifications and substitutions may be incorporated in such embodiments without departing from the spirit of the invention as defined by the claims which follow.

We claim:

1. In a pump, the combination of:

(a) a housing provided therein with an impeller chamber having a peripheral wall and having an impeller ax1s;

(b) an impeller rotatable in said impeller chamber about said impeller axis;

FIGS. 19 and 20 show the port 52 as containing a assess? (c) said impeller being provided with bendable elastomeric vanes having outer edges slidable along said peripheral wall of said impeller chamber as said impeller rotates therein;

(d) said peripheral wall including inlet and outlet cam surfaces respectively having increasing and decreasing radii, measured from said impeller axis, in the direction of rotation of said impeller;

(e) inlet and outlet ports respectively formed in said inlet and outlet cam surfaces;

(f) removable bridge means in at least one or" said ports and supporting said outer edges of said vanes as they slide across said one port; and

(g) means for removaoly securing said bridge means in place in said one port.

2. A pump as set forth in claim 1 wherein there is substantially point contact between said bridge means and said housing within said one port.

3. A pump as set forth in claim 1 wherein there is substantially line contact between said bridge means and said housing Within said one port, along at least one line extending in the direction of flow through said one port.

4. A pump as set forth in claim 1 wherein said bridge means includes a bridge surface slidably engageable by said outer edges of said vanes, and extending in the direction of sliding movement of said outer edges of said vanes across said one port.

5. A pump as set forth in claim 4 wherein said means for securing said bridge means in place includes means for maintaining said bridge surface oriented in the direction of sliding movement or" said outer edges of said vanes across said one port.

6. A pump as set forth in claim 1 wherein said bridge means includes resilient bridge elements biased laterally outwardly into engagement with the side walls of said one port and providing bridge surfaces slidably engageable by said outer edges of said vanes.

7. A pump as set forth in claim 6 wherein said bridge surfaces extend in the direction of sliding movement of said outer edges of said vanes across said one port.

8. A pump as set forth in claim 6 wherein said bridge surfaces extend radially of said one port. I

9. A pump as set forth in claim 1 wherein said bridge means includes a tubular bridge element spaced laterally inwardly from the side walls of said one port and terminating at its radially inner end in an annular bridge surface substantially concentric with said one port and slidably engageable by said outer edges of said vanes.

it). A pump as set forth in claim It wherein said means for securing said bridge means in place includes detents on said bridge means insertable into detent recesses in the side Walls of said one port.

References tilted UNETED STATES PATENTS 2,663,263 12/1953 Mayus et al. 103-117 2,855,853 10/1958 Yaugher et al. 103-117 2,933,046 4/1960 McCray 103117 3,122,102 2/1964 Leverett 103-117 3,303,791 2/1967 Doble 103l17 LAURENCE V. EFNER, Primary Examiner. WELBUR I. GOODLIN, Examiner. 

1. IN A PUMP, THE COMBINATION OF: (A) A HOUSING PROVIDED THEREIN WITH AN IMPELLER CHAMBER HAVING A PERIPHERAL WALL AND HAVING AN IMPELLER AXIS; (B) AN IMPELLER ROTATABLE IN SAID IMPELLER CHAMBER ABOUT SAID IMPELLER AXIS; (C) SAID IMPELLER BEING PROVIDED WITH BENDABLE ELASTOMERIC VANES HAVING OUTER EDGES SLIDABLE ALONG SAID PERIPHERAL WALL OF SAID IMPELLER CHAMBER AS SAID IMPELLER ROTATES THEREIN; (D) SAID PERIPHERAL WALL INCLUDING INLET AND OUTLET CAM SURFACES RESPECTIVELY HAVING INCREASING AND DECREASING RADII, MEASURED FROM SAID IMPELLER AXIS, IN THE DIRECTION OF ROTATION OF SAID IMPELLER; (E) INLET AND OUTLET PORTS RESPECTIVELY FORMED IN SAID INLET AND OUTLET CAM SURFACES; (F) REMOVABLE BRIDGE MEANS IN AT LEAST ONE OF SAID PORTS AND SUPPORTING SAID OUTER EDGES OF SAID VANES AS THEY SLIDE ACROSS SAID ONE PORT; AND (G) MEANS FOR REMOVABLY SECURING SAID BRIDGE MEANS IN PLACE IN SAID ONE PORT. 